TemplateBooleanModel.java

/*
 * Copyright 2014 Attila Szegedi, Daniel Dekany, Jonathan Revusky
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package freemarker.template;


/**
 * "boolean" template language data type; same as in Java; either {@code true} or {@code false}.
 * 
 * <p>
 * Objects of this type should be immutable, that is, calling {@link #getAsBoolean()} should always return the same
 * value as for the first time.
 */
public interface TemplateBooleanModel extends TemplateModel {

    /**
     * @return whether to interpret this object as true or false in a boolean context
     */
    boolean getAsBoolean() throws TemplateModelException;
    
    /**
     * A singleton object to represent boolean false
     */
    TemplateBooleanModel FALSE = new FalseTemplateBooleanModel();

    /**
     * A singleton object to represent boolean true
     */
    TemplateBooleanModel TRUE = new TrueTemplateBooleanModel();
    
}